Process for loosening the fiber structure of tanned furs



3,549,495 PROCESS FOR LOOSENING THE FIBER STRUCTURE OF TANNED FURS Rolf Monsheimer, Darmstadt-Eberstadt, and Ernst Pileiderer, Darmstadt-Arheilgen, Germany, assignors t Rohm & Haas G.m.b.H., Darmstadt, Germany No Drawing. Filed Feb. 12, 1968, Ser. No. 704,525 Claims priority, application Germany, Feb. 17, 1967, R 45,303 Int. Cl. C12b 1/00 US. Cl. 195-6 5 Claims ABSTRACT OF THE DISCLOSURE Method for loosening the fiber structure of furs to improve pliability by treating tanned furs with proteolytic enzymes. Suitable enzymes include mold-fungus, bacterial, and pancreatic proteases.

The present invention relates to a process for treating furs with a proteolytic enzyme after tanning to loosen the fiber structure of the tanned skins.

It is known in the art to soak raw furs in the presence of proteolytic enzymes and to subject furs to a special treatment with proteolytic enzymes after soaking. By this process, the fiber structure of the furs is loosened and the pliability of the furs is improved. However, the enzyme treatment must always be terminated before the fastness of the hairs is affected. For this-reason, the degree of softening desirable for subsequent fashioning of the finished furs into garments is not reached, as a rule.

A process has now been found by which a loosening of the fiber structure of furs and an improvement in pliability can be brought about even in furs which are already dressed. According to the present invention, the furs are treated with proteolytic enzymes after treatment with a tanning agent. It is surprising that the proteins of the furs are still susceptible to enzymatic action after tanning and that, nevertheless, a loosening of the hairs is not observed after this treatment with enzymes. The wellknown tendency of furs to stiffen on storage or under the influence of moisture is decreased by treatment according to this invention. Furs in which a hardening of this sort has already taken place can be softened by treatment according to the present invention even after long storage.

The proteolytic enzymes already known in the leather industry and in the dressing of furs are employed in the present invention, which resides not in the use of novel enzymes but in the use of known enzymes on furs after tanning. Preferably the enzymes are used in that pH range at which they show their greatest efficiency. For example, mold fungus proteases are suitably used at a pH of 4.5 to 6, bacterial proteases at a pH of 5 t0 7, and pancreatic tryptases at pH values over 6.5. Mold fungus proteases, for example of the type which can be obtained from Aspergilli such as Asp. niger, Asp. orycae, 0r Asp. flavus, from Streptomyces sp., or Clostridium acetobutylicum, are used to special advantage. Among the bacterial proteases, those of Bacillus subtilis and Bacillus mesentericus have proved good in the process of the invention. Trypsin, papain, and pepsin are also suitable enzymes.

Furs are suitably treated with such enzymes at temperatures between about 20 C. and about 60 C., preferably from about 40 C. to 50 C. Treatment times may be between 2 to 20 hours, depending on the nature of the fur being treated and the temperature of treatment, shorter treatment times being used at higher temperatures.

1 The range of the amount of enzyme product is between 0.2 5.0% (by weight of the dressed furs), said product having a proteolytic activity corresponding to an enzyme value of about 5,00012,000.

United States Patent 0 Patented Dec. 22, 1970 Advantageously, the enzymes are used in the presence of reducing compounds of divalent or tetravalent sulfur, such as sodium bisulfite, sodium sulfite, or sodium hyposulfite.

The enzyme treatment can take place directly after dressing. Suitably, the furs are stored for a day after removal from a tanning bath and are then introduced into an enzyme bath after a short intermediate rinsing. If the enzyme is permitted to work on furs taken directly from a tanning bath, without storage, considerable enzyme losses may arise because of reaction of the enzyme with tanning agent as yet unreacted with skin protein. These losses are still greater if enzyme is added directly to a tanning bath when tanning is completed.

The enzyme treatment according to the present invention is carried out with particular advantage as an adjunct to the finishing of dressed furs, i.e., after dazzling, bleaching, pickling, dyeing, and fat-liquoring. The enzyme can be added directly to the fat-liquoring bath after absorption of most of the fat, which is particularly economical, or can be used in a separate bath, optionally after a short intermediate rinsing. It is not necessary to deactivate the enzyme after a successful treatment.

The process of the invention is equally applicable to wild animal furs as well as to the furs of ranch animals.

A better understanding of the present invention and of its many advantages will be had by referring to the following specific examples, given by way of illustration. After being treated as described in each of the following examples, the furs were slowly dried and then posttreated mechanically (staking and drumming). The furs so obtained, when compared with furs not subjected to the enzyme treatment of the invention, are lighter and more pliable. The stretch of Persian lamb skins is increased by from 10 to 20 percent, which permits a corresponding decrease in the amount of fur needed in the preparation of items of fur clothing. The hardening which often is observed in furs on storage is avoided.

EXAMPLE 1 A bacterial protease was added to conventionally dressed and finished lambskins while present in a fatliquoring bath, in an amount of 2.0 grams of protease per liter of liquor. Proteases from cultures of Bacillus subtilis or Bacillus mesentericus can be employed. The bath had a pH of 5.0 to 5.5, and a temperature of 50 C. After a treatment time of two hours, the bath was drawn off and the furs were rinsed for a short time.

EXAMPLE 2 Calfskins were dressed and finished in the usual manner. After dyeing and fat-liquoring, the skins were rinsed with water at 50 C. and additional water at 50 C. was added so that the furs were just covered. The bath acquired a pH of 5.0 to 5.5 as a result of the treatment just described. At this point, 4.0 grams of a mold fungus tryptase prepared from a culture of Aspergillus orycae were added per liter of bath. The bath was agitated for two hours and the skins were then rinsed for a short period.

EXAMPLE 3 Persian lambskins were dressed and finished as usual. 4.0 grams of a mixture of mold fungus tryptase prepared from a culture of Aspergillus flavus, and pancreatic protease and 1 gram of sodium bisulfite were added per liter of the dyeing and fat-liquoring bath. After a treatment time of two hours, the bath was removed and the skins were rinsed for a short time.

What is claimed is:

1. A process for loosening the fiber structure of furs to improve pliability by treating the furs with a proteolytic enzyme after tanning.

2. A process as in claim 1 wherein said furs are treated References Cited With an enzyme in the presence of a reducing compound Lloyd et a1, Progress in Leather Science, of divalent or tetravalent sulfur. 1948 3. A process as in claim 1 wherein said proteolytic enzyme is a mold fungus protease 5 A. LOUIS MONACELL, Primary Examiner 4. A process as in claim 1 wherein said furs are treated with a proteolytic enzyme after fat-liquoring. NATH Asslstant Exammer 5. A process as in claim 1 wherein said furs are treated with a proteolytic enzyme in a fat-liquoring bath after absorption of most of the fat therefrom. 10 8 94,2 

